Read status on chat

I have just included a chat in my APP following the steps of the tutorial, however, I find that it makes a large number of entries in the database for the user’s reading states.
Every time a user reads a pending message it creates “Read”.

I’ve tried to do this through True/False and have it updated, but for some reason… it doesn’t allow me to update a True/False.

Is there any other way to do it that only takes 1 row per conversation and user?